Market Power and Collusion on Interconnection Phone Market in Tunisia : What Lessons from International Experiences

We try in this paper to characterize the state of mobile phone market in Tunisia. Our study is based on a survey of foreign experience (Europe) in detecting collusive behavior and a comparison of the critical threshold of collusion between operators in developing countries like Tunisia. The market power is estimated based on the work of Parker Roller (1997) and the assumption of "Balanced Calling Pattern". We use then the model of Friedman (1971) to compare the critical threshold of collusion. We show that the "conduct parameter" measuring the intensity of competition is not null during the period 1993-2011. Results show also that collusion is easier on the Tunisian market that on the Algerian, Jordanian, or Moroccan one

Controlling the Stability and the Electronic Structure of Transition Metal Dichalcogenide Single Layer under Chemical Doping

International audienc

Tuning the Magnetic and Electronic Properties of Monolayer Chromium Tritelluride through Strain Engineering

International audienc

Dependence of hole effective mass on nitrogen concentration in W-type strained InAs(N)/GaSb/InAs(N) quantum well lasers

We have investigated the effects of nitrogen N concentration on the properties of hole subbands and effective mass in dilute-nitride type-II InAsN/GaSb laser diodes on InAs substrate with “W” design. Using a 5-bands k·p model, we obtained interesting numerical results for the heavy-hole (hh) and the light-hole (lh) subbands. The hole effective masses were found to be very sensitive to the nitrogen concentration and to the differences in the Luttinger parameters between the well and the barrier. In addition, the hole effective masses are found to be strongly affected by band-anticrossing (BAC) model

Effect of nitrogen concentration on the electronic and vibrational properties of zinc-blende InN xP 1-x (x > 0.01)

Taking into account the recent advances in the epitaxial growth of single-crystal InN leading to a drastic re-evaluation of its fundamental energy band gap, we have studied the electronic properties of InN xP 1-x (x > 0.01) ternary alloy. Using the empirical pseudopotential method under the virtual crystal approximation, combined with the Harrison bond orbital model, the band gap at Γ, X and L points, the effective masses of the Γ valley and the electronic charge densities are calculated as a function of nitrogen composition. The fitted expressions of the energy band gaps indicate that the bowing parameter at Γ reached a broad value for very low nitrogen incorporation ( $x\le 1\%$ ). Furthermore, the band gap at Γ point decreases drastically with increasing nitrogen composition up to 1%. The elastic constants and the optical phonon frequencies are also reported. Our theoretical results provide a good agreement with the available data. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 200671.20.Nr Semiconductor compounds, 71.15.-m Methods of electronic structure calculations, 71.15.Dx Computational methodology,

A theoretical study of band structure properties for III-V nitrides quantum wells

Reliable and precise knowledge about the strain and composition effects on the band structure properties is crucial for the optimization of InGaN based heterostructures for electronic and optoelectronic device applications. AlInGaN as quaternary barrier material permits to control the band gap and the lattice constant independently. Using the model solid theory and the multi-band k.p interaction model, we investigate the composition effects on band offsets and band structure for pseudomorphic Ga1−xInxN/AlzInyGa1−y−zN (001) heterointerfaces having zinc-blende structure. The results show that both conduction and valence band states are strongly modified while varying In and Al contents in the well and barrier materials. Furthermore, it is found that using AlInGaN as the barrier material allows the design of heterostructures including InGaN wells with tensile, zero or compressive strain. Such results give new insights for III-nitride compounds based applications and especially may guide the design of white-light emission diodes

Interfaces as design tools for InAs/Gasb/InSb short-period superlattice for mid-infrared emission

International audienc

Modelling of an InAs/GaSb/InSb short-period superlattice laser diode for mid-infrared emission by the k.p method

International audienc